[097/119] hso: fix soft-lockup

Greg KH
2009-12-07T00:19:18Z

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2.6.31-stable review patch. If anyone has any objections, please let us know.

------------------
From: Antti Kaijanmäki <antti.kaijanmaki@nomovok.com>

commit dcfcb256cc23c4436691b0fe677275306699d6a1 upstream.

Fix soft-lockup in hso.c which is triggered on SMP machine when
modem is removed while file descriptor(s) under /dev are still open:

old version called kref_put() too early which resulted in destroying
hso_serial and hso_device objects which were still used later on.

Signed-off-by: Antti Kaijanmäki <antti.kaijanmaki@nomovok.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

---
drivers/net/usb/hso.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -1362,7 +1362,7 @@ static void hso_serial_close(struct tty_
/* reset the rts and dtr */
/* do the actual close */
serial->open_count--;
- kref_put(&serial->parent->ref, hso_serial_ref_free);
+
if (serial->open_count <= 0) {
serial->open_count = 0;
spin_lock_irq(&serial->serial_lock);
@@ -1382,6 +1382,8 @@ static void hso_serial_close(struct tty_
usb_autopm_put_interface(serial->parent->interface);

mutex_unlock(&serial->parent->mutex);
+
+ kref_put(&serial->parent->ref, hso_serial_ref_free);
}

/* close the requested serial port */